When James McHugh Construction Co. set about planning the erection of a Potain tower crane for a 44-story residential and parking facility in downtown Chicago, Ill., the company knew it needed a mobile crane that could maneuver easily, circumventing traffic and other city impediments. The mobile crane also needed a long enough boom to reach skyscraper heights. The Grove GMK6300L — the first to be used in North America — was a natural choice to get the Potain MD 485 B ready for work on the $111-million site.
Paul Treacy, superintendent for McHugh, said that with its mobility and extra-long boom reach, the GMK6300L is ideal for city projects.
“Chicago construction regulations mandate that cranes can’t be on the streets during rush hour. We knew that with the GMK6300L, we could easily move and set up the crane at the job site without breaching traffic laws,” he said. “A key reason for this is the exceptionally long boom on the GMK6300L, which meant for rigging the Potain we didn’t need a jib. For other cranes to get similar reach, you have to swing the jib in and set up the crane again, which costs considerable amounts of time.”
The GMK6300L’s five-axle MEGATRAK independent, hydro-pneumatic suspension system and all-wheel drive made it easy to navigate Chicago’s city streets. Also on board the crane is the ECOS electronic crane operating system, which programs essential duties and supplies information to the operator; and EKS 5, which monitors lifting conditions and provides a full graphic display of telescoping percentage and load charts. A choice of five outrigger positions gives the GMK6300L more flexibility than any other in its class.
“We’re lucky to have the experience of the first GMK6300L in North America,” Treacy said. “With its lengthy boom, dynamic suspension and heavy lifting capacity, it seems no job will be too tall, too rugged or too heavy for this machine.”
The Potain MD 485 B tower crane will provide all the main lifting assistance for the high-rise job.
“Having the SMDM trolley on the MD 485 B is a huge advantage for us,” Treacy said. “It’s very quick to change from a two-part line to a four-part line, depending on the lifting requirements.”
To rig the tower crane, the GMK6300L lifted its mast and jib sections, weighing between 8,500 lbs and 9,000 lbs. The GMK6300L’s seven-section, 80 m boom allows for exceptionally heavy lifts, while the Megaform shaping offers greater rigidity and the Twin-Lock pinning makes for a lighter boom design, which allows greater loads to be lifted.
A Grove RT880 rough-terrain crane also worked on assembly of the Potain tower crane and that crane is still on the project. When setup of the MD 485 B tower crane was completed, the rough-terrain crane set about pouring concrete, placing formwork, hoisting mechanical equipment, lifting structural steel and performing other job site services. The RT880 has a boom of 39 m that can be extended to 70.7 m when using the full complement of jib attachments.
All three cranes were recommended and leased to James McHugh Construction Co. by Central Contractors Service in Chicago, a member of the ALL Erection & Crane Rental Corp. family of Companies. Central used its 3D Lift Plan technology to visualize and plan the erection of the tower crane on the site. The job in Chicago is set to finish February 2014.